(declare-sort E 0)

(declare-fun s () (Set E))
(declare-fun t () (Set E))
(declare-fun u () (Set E))
(assert (< (card (union s t)) 4))
(assert (>= (card (union s u)) 1))
(assert (< (card (union t u)) 3))
(assert (< (card s) 4))
(check-sat)
